GUACAMOLE-2181: Rely on automatic stack traces for debug-level logs.

extensions/guacamole-auth-restrict/src/main/java/org/apache/guacamole/host/HostRestrictionParser.java

@@ -64,8 +64,7 @@ public class HostRestrictionParser {
                 addressList.add(hostName);
             }
             catch (HostNameException e) {
-                LOGGER.warn("Invalid host name or IP: {}", host);
-                LOGGER.debug("HostNameException.", e.getMessage());
+                LOGGER.warn("Invalid host name or IP: {}", host, e);
             }
             
         }